The BioCycle Study was a prospective longitudinal cohort study comprising 259 women aged 18 to 44 years (98% follow-up rate) followed for two menstrual cycles (2005-2007). The study was designed to better understand menstrual cycle function and the intricate relationships between reproductive hormone levels and oxidative stress. Since completion of the study, much progress has been made in the analysis of the BioCycle Study data. To date, over 80 papers have been published. The BioCycle Study has contributed substantially to the fields of nutritional, environmental, and social epidemiology, offering valuable insights into various factors associated with premenopausal womens reproductive and cardio-metabolic health. In particular, several dietary factors have been evaluated with regard to their associations with reproductive hormones and ovulation, including dietary minerals such as sodium and manganese (Kim et al. Br J Nutr 2018). These findings have highlighted the important role of diet in reproductive function. Further research evaluating potential environmental factors, including bisphenol A, chlorophenols, benzophenones, and parabens, found that mixtures of phenols were associated with changes in reproductive hormones which has potential implications for reproductive health (Pollack et al. Environ Int 2018). In addition, it was also observed that tampon use was associated with elevation in mercury levels and oxidative stress biomarkers, indicating that tampons may be a potential source of exposure to metals and chemicals that have been largely ignored (Singh et al. Environ Health 2018). Further research into the mechanisms driving these associations is needed to understand the potential implications for women's health. Overall, this body of work has been influential in describing not only the short-term impact of diet and lifestyle on hormonal function and markers of menstrual cycle dysfunction (e.g., anovulation, luteal phase deficiency, and abnormal menses) but their potential long-term impact on chronic disease risk. The team intends to build upon its current findings from the BioCycle Study to fill critical research gaps in its quest to answer important public health questions for women of reproductive age.